A Repeated Biopsy by EBUS-TBNA Contributed to the Selection of an Appropriate Therapeutic Regimen for a Lung Cancer Patient.

Since the development of third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors for lung cancer treatment, the need for a rebiopsy has increased. To select an appropriate therapeutic regimen, the genetic alterations in cancerous tissue should be determined. A rebiopsy plays an important role in the treatment of patients with diseases that are refractory to the previous generation of EGFR tyrosine kinase inhibitors. Cell-free DNA-based exploration is useful for determining the cause of treatment resistance in cases in which a rebiopsy is difficult; however, this method cannot detect histologic changes (a mechanism of resistance), which may lead to the selection of nonoptimum therapeutic agents. We herein report a case in which EGFR mutation-positive (exon 19 deletion) lung cancer was successfully treated with an appropriate chemotherapeutic regimen after disease progression. The regimen was selected based on the precise evaluation of a rebiopsy specimen, which determined the histologic type and detected a gene mutation.